The present invention relates generally to work machines, and more particularly to work machines having a tilt mechanism for tiltably supporting a working body position relative to a ground engaging, running gear portion.
Since work machines such as track-type swing machines for forestry applications are often used off-road on uneven terrain, the frame and thus the working body may not be horizontal relative to the horizon when the work machine is located in a work performing position. It is highly desirable, however, for the comfort of the operator and for the most efficient functioning of the work machine that the working body be horizontal during work machine operation. Accordingly, it is useful to equip track-type swing machines with a tilting mechanism such that the operator can maintain the working body horizontal even when the frame of the work machine is inclined at an angle relative to the horizon.
In addition, the tilt mechanism allows the operator to tilt the working body such that the work machine is more capable of maneuvering in close quarters, for example, maneuvering between rows of trees which are positioned close together.
An example of a currently used tilt mechanism is shown in U.S. Pat. No. 5,337,847, issued Aug. 16, 1994 to Woods et al. (hereafter referenced as ""847). ""847 discloses a four-way leveling mechanism which uses a spherical bearing mounted on a shaft and vertical hydraulic cylinders to accomplish the tilt function. This type of tilt mechanism causes the work machine to have a high center of gravity due to the operating clearance needed for the vertically mounted hydraulic tilt cylinders, causing operator discomfort and fatigue. This operating clearance also lowers the ground clearance for the work machine. In uneven terrain often encountered by these work machines, high ground clearance helps prevent damage to the work machine often caused by stumps and other ground-resident debris. The low ground clearance and high operating clearance of the prior art can combine to make maintenance and servicing more difficult, as well. The tilt cylinders may be subject to high shock and moment forces due to their arrangement relative to the pivot point of the tilt mechanism of the machine.
The present invention is directed to overcoming one or more of the problems as set forth above.
In one aspect of the present invention, a work machine is disclosed having a base frame, a track assembly, a support tilt frame, a center tilt frame, an upper tilt frame, a working frame, and a coupling mechanism. The coupling mechanism includes a pitch support member, a roll support member, and a pitch pivot link. The pitch support member connects one of the tilt frames and the pitch pivot link, and the roll support member connects the pitch pivot link and another of the tilt frames.